Electrical connector with continuous strip contacts

ABSTRACT

An electrical connector contact strip including spaced electrical contacts, a body and fusible elements. The spaced electrical contacts each have a main section and a tab section extending from an end of the main section. The body includes dielectric material molded onto the contacts and connecting the contacts to each other. The fusible elements are mounted on the tab sections.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electrical connectors and, moreparticularly, to a continuous strip of contacts secured in a housing toform an electrical connector.

2. Brief Description of Earlier Developments

U.S. Pat. No. 3,500,295 discloses an electrical connector with terminalsconnected by an injection-molded elongate body which is embedded in asupporting structure. PCT publication No. WO 98/15989, hereinincorporated by reference, discloses a high density electrical connectorwith contacts having solder balls. A deformable element in an opening inthe housing frictionally retains the contact.

A problem exists with conventional connectors in that solder can move bywicking into a contact area of a contact, when the solder is melted,which can interfere with a connection at the contact area. Anotherproblem exists with conventional connectors in that different sizes ofconnectors having different row lengths and array sizes requiredifferent tooling to manufacture. Another problem exists withconventional connectors in that effects of differential coefficient ofthermal expansion in a direction transverse to trip direction can causedamage to soldered connections. Another problem exists with conventionalconnectors in that tensile failures can occur in the connection of asolder ball to a contact. The present invention can help to overcomethese problems and provide other advantages.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, anelectrical connector contact strip is provided comprising spacedelectrical contacts, a body and fusible elements. The spaced electricalcontacts each have a main section and a tab section extending from anend of the main section. The body comprises dielectric material moldedonto the contacts and connecting the contacts to each other. The fusibleelements are mounted on the tab sections.

In accordance with another embodiment of the present invention anelectrical connector is provided comprising a housing; and at least tworows of electrical connector contact strips connected to the housing.Each contact strip has electrical contacts connected to each other by abody comprising dielectric material. The contact strips are movablycaptured by their bodies in the housing.

In accordance with another embodiment of the present invention, anelectronic component assembly is provided comprising a first electroniccomponent comprising a printed circuit board; and an electricalconnector connected to the printed circuit board. The electricalconnector comprises a housing and a plurality of contact stripsconnected to the housing. The contact strips each comprising electricalcontacts connected to each other by a body. The bodies are movablycaptured in the housing such that the bodies can move relative to eachother.

In accordance with one method of the present invention, a method ofassembling an electrical connector is provided comprising steps offorming electrical contact strips, each strip comprising electricalcontacts connected to each other by a dielectric body; and mounting thestrips by their bodies to a housing, wherein the bodies are movablycaptured by the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the present invention areexplained in the following description, taken in connection with theaccompanying drawings, wherein:

FIG. 1 is an exploded partial cross-sectional elevational view of anelectronic assembly incorporating features of the present invention;

FIG. 2 is a partial perspective view of one of the contact strips usedin one of the electrical connectors shown in FIG. 1;

FIG. 3 is a cross-sectional view of the contact strip shown in FIG. 2taken along line 3—3;

FIG. 4 is a perspective view of one of the connectors shown in FIG. 4;

FIG. 5 is a partial cross-sectional view taken along line 5—5 in FIG. 4;

FIG. 6 is a partial perspective view of the other one of the contactstrips shown in the second connector shown in FIG. 1;

FIG. 7 is a partial cross-sectional view of an alternate embodiment ofthe first electrical connector;

FIG. 8 is a perspective view of the housing of another alternateembodiment of the electrical connector;

FIG. 9 is a partial cross-sectional view of an alternate embodiment ofthe electrical connector using the housing shown in FIG. 8;

FIG. 10A is a partial front elevational view of contacts attached to acarry strip;

FIG. 10B is a partial front elevational view of the contacts shown inFIG. 10A with the body of a contact strip formed onto the contacts;

FIG. 10C is a partial front elevational view as in FIG. 10B with thecarry strip removed;

FIG. 11 is a partial perspective view of an alternate embodiment of thecontact strip;

FIG. 12A is a cross-sectional view of an alternate embodiment of theelectrical connector having contact strips as shown in FIG. 11; and

FIG. 12B is a cross-sectional view of the connector shown in FIG. 12Ataken along line 12B—12B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, there is shown an exploded elevational view of anassembly 10 incorporating features of the present invention. Althoughthe present invention will be described with reference to theembodiments shown in the drawings, it should be understood that thepresent invention can be embodied in many alternate forms ofembodiments. In addition, any suitable size, shape or type of elementsor materials could be used.

The assembly 10 generally comprises a first electronic componentassembly 12 and a mating second electronic component assembly 14. Inthis embodiment the first assembly 12 generally comprises a firstcircuit substrate, such as a printed circuit board 16 and a firstelectrical connector 18. The second assembly 14 generally comprises asecond circuit substrate, such as a printed circuit board 20 and asecond electrical connector 22. However, in alternate embodiments theconnectors 18, 22 could be attached to different types of electroniccomponents other than printed circuit boards. Referring also to FIGS.2-4, the first connector 18 generally comprises a housing 23 and stripsof contacts 26. Each strip defines a row of contacts. The housing 23 ispreferably comprised of molded plastic or polymer dielectric material,such as a liquid crystal polymer (LCP). In this embodiment the housing23 is comprised of two housing pieces 24, 25. However, in alternateembodiments the housing 23 could be comprised of only one or more thantwo pieces. In another alternate embodiment, the housing piece 24 mayinclude features, such as solder pads or standoffs (not shown), thathelp in mounting the housing to the first printed circuit board 16.However, any suitable means can be provided for attaching the housing tothe first printed circuit board. In this embodiment the housing piece 24has receiving areas 30 for receiving the contact strips 26. FIG. 4 showsonly one contact strip 26 in the receiving areas 30 merely for the sakeof clarity. In actual practice all the receiving areas 30 wouldpreferably have contact strips 26 located therein. In the embodimentshown, the housing piece 24 has five receiving areas 30 aligned parallelto each other as straight slots which extend entirely through thehousing piece 24 between the two sides 32, 34. However, in alternateembodiment any suitable number of receiving areas 30 could be provided.In this embodiment the receiving areas 30 can each hold a contact strip26 of four of the contacts 27. However, in alternate embodiments eachreceiving area 30 can hold any suitable number of contacts 27. As seenbest in FIG. 5, each receiving area 30 could have opposing inwardlyprojecting ledge 36 proximate the side 32. The second housing piece 25is attached to the first housing piece 24 and has areas 38 with thecontacts 27 therein for receiving portions of the contacts in the secondelectrical connector 22. However, in alternate embodiments any suitabletype of housing can be provided.

The contact strips 26 are adapted to be inserted into the housing 23 ina modular assembly fashion. The strips 26 can each comprise a body 40,the contacts 27, and formed bodies, such as solder balls 42. The body 40is preferably a one-piece molded plastic or polymer member which ispreferably over-molded onto the contacts 27. However, in an alternateembodiment the body 40 could be formed separate from the contacts 27with the contacts 27 being subsequently inserted into the body 40.Over-molding the body onto the contacts causes the body 40 to functionas a seal 401 between the two opposite sections 46, 48 of the contacts27 to prevent solder from the solder ball 42 wicking up the contact 27during a reflow operation used to secure the connector 18 to the printedcircuit board 16. Thus, a suitable amount of solder is available tosurface mount connector 18 and the contact surface of the male contactsection 46 is prevented from being contaminated by solder.Alternatively, contacts 27 could have any suitable type of connection atthe two end sections 46, 48. For example, the contacts 27 could havesurface mount tails.

In a preferred method of manufacturing the strips 26, the contacts 27are connected to each other as a unitary contact blank. The body 40 isover-molded onto the contact blank. Then the contact blank is cut toremove connecting sections to thereby electrically isolate theindividual electrical contacts 27 from each other. However, the body 40maintains a structural connection among the contacts 27 in the strip 26.Preferably, the strips 26 are manufactured as a substantially continuousstrip which is rolled onto a reel and subsequently cut intopredetermined lengths of the contacts 27 for assembly into housings. Inan alternate method of manufacturing the contact strip the body could bepreformed and the contacts could be inserted into the preformed body.

Each contact 27 is preferably stamped and formed from a sheet ofconductive material, such as copper alloy. Each contact has a centersection 44 and two end sections 46, 48. A first one of the end sections46 extends from the body 40 and forms a contact area, such as theblade-type contact area shown in FIG. 2, or the dual beam contact shownin FIG. 6, or any other suitable arrangement. The second end section 48extends from the opposite end of the body 40 and could have a solderball mounting tab for mounting the solder ball 42 to the contact 27.When using a solder ball, the tab 48 can have a dovetail shape with twopockets 50 between the tab 48 and the center section 44. The material ofthe solder ball 42 extends into the pockets 50 to retain the solder ball42 on the contact 27 prior to mounting of the connector 18 to the firstprinted circuit board 16. However, other shapes of the contacts 27 andother features could be provided.

The body 40 generally comprises main sections 52 and interconnectingsections 54. The main sections 52 surround individual ones of the centersections 44 of the contacts 27. The contacts 27 include notches 47 inthe center section 44. When the body 40 is molded onto the centersection 44 the material of the body 40 extends into the notches 47. Thisforms an interlocking of the contacts 27 to the body 40 to retain thecontacts with the body. However, any suitable system for connecting thecontacts with the body could be provided. The interconnecting sections54 connect the main sections 52 of each strip 26 to each other inseries. In one embodiment, the main sections 52 comprise tapered topedges 56. The main sections 52 are sized and shaped to very closely fitinside the receiving areas 30. Alternatively, strip 26 could beinterference fit within receiving areas 30. The top edges 56 interactwith the ledges 36 to retain the body 40 with the housing piece 24 priorto mounting the first connector 18 to the first printed circuit board16. The interconnection sections 54 are smaller than the main sections52 and are adapted to both space the main sections 52, and theirrespective contacts 27, from each other in each strip 26 at fixedlocations and, allow for relatively easy cutting or severing of theinterconnection sections 54 to form the multiple strips 26 from a reelof a relatively long single contact strip. In alternate embodiments themain sections 52 and interconnection sections 54 could have any suitableshape. Alternative and/or additional means could also be used toassemble the contact strips 26 with the housing piece 24.

Referring now to FIGS. 1 and 6, the second electrical connector 22generally comprises a second housing 60 and electrical connector contactstrips 62. The second housing 60 has slots 64 therethrough whichfunction as receiving areas for the contact strips 62 similar to thereceiving areas 30 in the first housing piece 24. The second housing 60is adapted to be fixedly connected to the second circuit substrate, suchas a printed circuit board 20. The second housing 60 has a perimeterwall that defines a receiving area 66 for aligning and receiving aportion of the first connector 18 therein. The contact strips 62 eachgenerally comprise a frame 68, electrical contacts 70 and formed bodies,such as solder balls 72. The frame 68 is substantially the same as theframe 52. The solder balls 72 are substantially the same as the solderballs 42. The electrical contacts 70 generally comprise two deflectablearms 74 which form mating area for receiving the first end section 46 ofthe first contacts 27. The arms 74 are sized and shaped to fit insidethe areas 38 of the first connector's housing 25, if used. The contactstrips 62 and housing 60 are connected to each other similar to thecontact strips 26 and housing piece 24.

This design concept over molds a continuous strip of contacts that havea solder ball soldering attachment on one end and a mating configurationon the other. The strip is produced on a matching pitch B. The stripsare cut to any desired length to construct a series of rows to form anarray that is positioned by another member that would hold them inposition to form this configuration. This design eliminates solderwicking into the contact area by the over molded section separating thetwo areas. This design provides flexibility for configuring various rowlengths and array sizes. For example, the same type contact strip can beused with different size housings merely by cutting the contact strip todifferent lengths such as for housings for holding strips of 8, 10, 20,30, or 40 contacts each. This design reduces the tooling cost forproducing multiple sizes by utilizing one component to produce manyvariations of sizes. This design is highly automatable in the form of acontinuous strip for significant cost savings. This design de-couplesthe effects of differential co-efficient of thermal expansion (CTE) inthe direction transverse to strip direction by utilizing rows ofterminals to construct an array configuration making the construction oflarge arrays feasible. The larger the size of the connector, the largerthe differential CTE. By decoupling the contacts 27, 70 in direction A,with the contacts being able to partial move or float relative to theirframes, the differential CTE among the various components can beaccommodated to prevent damage to the soldered connections to theprinted circuit boards. This design can incorporate a ball tab featurethat resist solder ball tensile failures.

Referring now to FIG. 7 a partial cross-sectional view of an alternateembodiment of the connector is shown. In this embodiment the connector100 includes a housing 102 and contact strips 104 (only one of which isshown) captured by the housing 102. The housing 102 generally comprisestwo housing pieces 106, 108. The contact strips 104 generally comprisecontacts 110, body 112, and formed bodies, such as solder balls 114. Thecontacts 110 and solder balls 114 are substantially the same as thecontacts 27 and solder balls 42. The main sections 116 of the body 112are substantially the same as the main sections 52, but have tapered topand bottom edges 118, 119. The housing pieces 106, 108 have inwardlyprojecting ledges 120, 121 at lateral sides of the receiving slots 122to capture the body 112 in the slots. The spacing between the lateralsides of the body 112 and the housing pieces at the slots 122 is suchthat the body 112 and their contacts 110 can slightly laterally move asindicated by arrow A.

Referring now to FIGS. 8 and 9 another alternate embodiment will bedescribed. In this embodiment the connector 200 has a housing 202 withtwo pieces 204, 206 that have an enlarged receiving area 208 sized andshaped to receive more than one contact strip. In this embodiment theconnector 200 has two different types of contact strips 210, 212. Thecontact strips 210, 212 have the same type of contacts 214 and solderballs 216, but their frames or bodies 218, 220 have different shapes.More specifically, the main sections of the bodies 218, 220 are sizedand shaped to mate with each other as shown. The bodies 218 aresubstantially the same as the bodies 112, but the bodies 220 haveoutwardly projecting ledges 222 on its top and bottom sides such thatthe bodies 218, 220 cooperate to capture each other within the receivingarea 208. In an alternate embodiment each contact strip could havealternating types of the bodies 218, 220.

Referring now to FIGS. 10A, 10B and 10C, one method of manufacturing acontact strip will be described. In this method, as seen in FIG. 10A,the contacts 27 are formed from a sheet 300 of conductive material. Thesheet 300 has been stamped and formed to provide a carry strip 302 thatconnects the contacts 27 to each other. The body, includinginterconnection sections 54, is then over-molded onto the contacts 47 asshown in FIG. 10B. As seen in FIG. 10C, the carry strip 302 is thenremoved from the contacts 27. The contacts 27 are, thus, spaced fromeach other and electrically isolated from each other. The body 40maintains the structural relationship of the contacts 27 relative toeach other after the carry strip 302 is removed.

Referring now to FIG. 11, an alternate embodiment of the contact strip26 is shown. In this embodiment the contact strip 310 generallycomprises contacts 27, a body 314, and fusible elements 42, such assolder balls. The body 314 generally comprises main sections 312 andinterconnecting sections 314. The main sections 312 include a lateralprojection 316 on one side 318 and a lateral recess 320 on an oppositeside 322. Referring also to FIGS. 12A and 12B, a plurality of thecontact strips 310 are shown connected to each other and with a housing324 to form a connector 326. The lateral projections 316 and recesses320 are sized and shaped to mate with each other to connect the strips310 to each other. In alternate embodiments any suitable shape of matingconnection between the strips could be provided. In this embodiment thehousing 324 includes a receiving area 328 to receive the strips 310. Thehousing 324 includes a projection 330 at one side of the receiving area328 and a recess 332 at an opposite side of the receiving area. Theprojection 330 extends into the recesses 320 of one of the strips 310.The recess 332 receives the projections 316 of another one of the strips310. Thus, the interlocking of the projections 316, 330 with therecesses 320, 332 connect the strips 310 with each other and the housing324. With this type of embodiment the strips 310 are not substantiallyconstrained in the plane shown in FIG. 12B.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

What is claimed is:
 1. An electrical connector contact strip comprising:a plurality of spaced electrical contacts, each contact having a mainsection and a tab section extending from an end of the main section; anover-molded body comprising dielectric material molded over thecontacts, wherein the body comprises main sections and interconnectsections which interconnect the main sections with each other in series,wherein the main sections surround portions of the contacts, and whereinthe contacts are connected to each other as a strip by the interconnectsections; and fusible elements mounted on the tab sections, wherein thefusible elements have portions located in pocket areas of the contactsto retain the fusible elements on the tab sections.
 2. An electricalconnector contact strip comprising: a plurality of spaced electricalcontacts, each contact having a main section, a tab section extendingfrom a first end of the main section, and a second end section; anovermolded body comprising dielectric material molded onto the contacts,wherein the contacts are connected to each other in series byinterconnect sections of the body; and fusible elements mounted on thetab sections, wherein the body forms a seal between the tab sections andthe second sections to prevent wicking of the fusible elements along thecontacts between tab sections and the second end sections.
 3. Anelectrical connector comprising: a housing; and at least two rows ofelectrical connector contact strips positioned in the housing, eachcontact strip comprising: a plurality of spaced main sections connectedto each other, each main section comprising a dielectric materialovermolded onto a separate electrical contact; wherein the contactstrips are movably captured by their bodies in the housing, wherein thehousing comprises rows of receiving areas for receiving the contactstrips, and wherein the receiving areas include inwardly projectingflanges at a top side of the housing.
 4. An electrical connectorcomprising: a housing; and at least two rows of electrical connectorcontact strips positioned in the housing, each contact strip comprisinga body and electrical contacts, each body comprising a plurality ofspaced main sections connected to each other, each main sectioncomprising a dielectric material overmolded onto a separate one of theelectrical contacts; wherein the contact strips are movably captured bytheir bodies in the housing, wherein the housing comprises at least twomembers, and wherein the contact strips are sandwiched between portionsof the two members to movably capture the contact strips in the housing.5. An electrical connector contact strip comprising: a plurality ofelectrical contacts connected to each other in a series, the contactseach comprising a first end, a second end, and a middle sectiontherebetween; fusible elements connected to the second ends of thecontacts, wherein the fusible elements comprise solder balls with thesecond ends of the contacts extending into the solder balls to therebyattach the solder balls with the second ends, and wherein the electricalconnector contact strip provides the contacts as a series of connectedfusible element mountable electrical contacts in a strip; and anovermolded body connecting the contacts to each other, wherein the bodyforms seals between the ends of the contacts to prevent wicking of thefusible elements along the contacts between the ends.
 6. A method ofassembling an electrical connector contact strip comprising steps of:providing a plurality of electrical contacts connected in series, eachcontact comprising a first end, a second end and a middle sectiontherebetween, wherein the contacts are comprised of stamped sheet metal;and attaching solder balls to the second ends of the contacts, thesecond ends of the contacts extending into the solder balls to therebyattach the solder balls with the second ends, wherein the electricalconnector contact strip provides the contacts as a series of connected,stamped sheet metal fusible element mountable electrical contacts in astrip which is adapted to be subsequently connected to a housing to forman electrical connector, wherein the step of providing the contactscomprises forming the second ends of the contacts with flat mountingtabs having pockets, and the step of attaching the solder ballscomprises locating portions of the solder balls in the pockets.